#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

typedef struct s_tree  *tree;
 
struct s_tree
{
  int			key, val;
  tree			ls, rs;
};


tree empty() 
{
	return NULL;
}

size_t size(tree t)
{
	return t!=NULL?1+size(t->ls)+size(t->rs):0;
}

size_t max(size_t a, size_t b)
{
  if (a<b)
    return b;
  else
    return a;
}

size_t height(tree t)
{
	return 0;
}
